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Ublas : |
From: Vardan Akopian (vakopian_at_[hidden])
Date: 2007-03-07 05:39:21
I think this is a perfect case to use index_data as Gunter suggested
before. So the loop in your FillOmegas() would become:
for (unsigned i = 0, iEnd = pathgatevector.filled(); i < iEnd; ++i) {
omegas (i) = othervector(pathgatevector.index_data()[i]);
}
On my machine, this reduces the runtime from 1 minute to 0.26 (using
the arguments 100000 1000 to your program)
-Vardan
On 3/6/07, Sourabh <sourabh_at_[hidden]> wrote:
> #include <boost/timer.hpp>
>
> #include <boost/numeric/ublas/matrix.hpp>
> #include <boost/numeric/ublas/triangular.hpp>
> #include <boost/numeric/ublas/io.hpp>
> #include <boost/numeric/ublas/matrix_sparse.hpp>
> #include <boost/numeric/ublas/matrix_proxy.hpp>
> #include <boost/numeric/ublas/operation.hpp>
> #include <boost/numeric/ublas/vector.hpp>
> #include <boost/numeric/ublas/vector_proxy.hpp>
>
> #include "../matrix/config.h"
>
> using namespace boost::numeric::ublas;
>
> vector<double> othervector (20000);
>
> void FillPathIncidenceVector (compressed_vector<double>& pathgatevector)
> {
> unsigned factor = 20;
> for (unsigned i = 0; i < pathgatevector.size (); ++ i) {
> if (i % factor == 0) {
> pathgatevector(i) = i;
> }
> }
> for (unsigned i = 0; i < othervector.size (); ++i) {
> othervector (i) = i * 0.1;
>
> }
>
> }
>
>
> void
> FillOmegas (vector<double>& omegas, compressed_vector<double>& pathgatevector)
> {
> omegas.resize ((pathgatevector.nnz ()));
> compressed_vector<double>::const_iterator it = pathgatevector.begin ();
> for (unsigned i = 0; it != pathgatevector.end (); ++it, ++i) {
> omegas (i) = othervector(it.index ());
> //omegas (i) = it.index ();
> //<< choice between the above two statements.>>
> }
>
> }
>
> int main ( int argc, char* argv[])
> {
> int iterations = atoi (argv[1]);
> int gatesperpath = atoi (argv[2]);
> boost::timer t;
> t.restart();
> compressed_vector<double> pathgatevector (gatesperpath * 20);
> FillPathIncidenceVector (pathgatevector);
> std::cout << t.elapsed () << std::endl;
> vector<double>omega;
> while (iterations--) {
> FillOmegas (omega, pathgatevector);
> }
> std::cout << t.elapsed() << std::endl;
> }
>
> On Tue, 6 Mar 2007, Gunter Winkler wrote:
>
> > On Tuesday 06 March 2007 13:58, Sourabh wrote:
> >
> > > > > Just a strange thing, if I change the statement
> > > > > densevector (i) = othervector (it.index ());
> > > > >
> > > > > to
> > > > >
> > > > > densevector (i) = (it.index ());
> > > > >
> > > > > time taken is increased. What could be the possible reason ?
> >
> > can you post a program that shows that behavior?
> >
> > mfg
> > Gunter
> > _______________________________________________
> > ublas mailing list
> > ublas_at_[hidden]
> > http://lists.boost.org/mailman/listinfo.cgi/ublas
> >
>
> --
> -- Sourabh
>
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